My questions:
Is it possible for airdrop sites to access your funds even after disconnecting your wallet?
Is there any other way wallet can be compromised aside this mistakes?
It's becoming scary day by day to leave huge amount of assets on wallet this days. Perhaps this is one of the reason some people still think everything about bitcoin and crypto entirely is a scam as funds lost can not be recovered. I will appreciate detail explanation on this and the solution to avoid future occurrence.
I'm not sure if you are aware there were some email bridge from Coingecko and some exchanges some weeks ago, anyone can have access to that leak emails and other sensitive information and if your email is one of those comprised, they can try those emails with the leak password and if you are the type of person that use simple password or general password, your email content could be exposed through this way.
It could also be that someone close to you have access to your phone or email login and you don't know about it, so do well and check your email activity if there has been an attempted login from other devices or just check the devices your email login into.
About been connected to aidrops, this is not the safest way to use a wallet address. When running airdrops, you should never use your main wallet to participate in any of the airdrops because you might be compel to interact with a smart contract and this contracts are hidden, you don't know what they means or what they are to do, you might end up exposing your entire wallet doing these aidrops, next time use a new wallets with nothing on the address to claim or participate in airdrops.